The present invention relates to a method and system for providing lawfully authorized electronic surveillance service in a Public Switched Telephone System (PSTN) and more particularly to configuring existing telephone networks using various types of switches to effectively and economically provide such service.
The written description uses a large number of acronyms to refer to various services, messages and system components. Although generally known, use of several of these acronyms is not strictly standardized in the art. For purposes of this discussion, acronyms therefore will be defined as follows:
Address Complete Message (ACM)
Advanced Intelligent Network (AIN)
American National Standards Institute (ANSI)
ANswer Message (ANM)
Automated Message Accounting (AMA)
Automatic Number Identification (ANI)
Call Processing Record (CPR)
Central Office (CO)
Common Channel Signaling (CCS)
Communications for Assistance for Law Enforcement Act (CALEA)
Custom Local Area Signaling Services (CLASS)
Federal Bureau of Investigation (FBI)
Generic Address Parameter (GAP)
Generic Data Interface (GDI)
Initial Address Message (IAM)
Integrated Service Control Point (ISCP)
Integrated Services Digital Network (ISDN)
ISDN User Part (ISUP)
Intelligent Peripheral (IP)
Local Access and Transport Area (LATA)
Local Number Portability (LNP)
Location Routing Number (LRN)
Multi-Services Application Platform (MSAP)
Numbering Plan Area (NPA)
Office Equipment (OE)
Origination Point Code (OPC)
Personal Communications Service (PCS)
Plain Old Telephone Service (POTS)
Point in Call (PIC)
Personal Identification Number (PIN)
Primary Rate Interface (PRI)
Public Switched Telephone Network (PSTN)
Records Accounting Office (RAO)
Record Change Memory Administration Center (RCMAC)
Remote Memory Administration System (RMAS)
Service Control Point (SCP)
Service Creation Environment (SCE)
Service Management System (SMS)
Service Switching Point (SSP)
Signaling System 7 (SS7)
Signaling Point (SP)
Signaling Transfer Point (STP)
Simplified Message Desk Interface (SMDI)
Speaker Identification/Verification (SIV)
Telecommunications Industry Association (TIA)
Terminating Attempt Trigger (TAT)
Time Slot Interchange (TSI)
Traffic Service Position System (TSPS)
Transaction Capabilities Applications Part (TCAP)
Transmission Control Protocol/Internet Protocol (TCP/IP)
Historically in the United States authorities such as city, state, or federal police authorities, may engage in electronic surveillance (frequently referred to in the vernacular as wire-tapping), when duly authorized to perform such an activity by a cognizant judicial authority. In earlier times, when public telephone service was virtually all analog the procedure was relatively simple. Assuming surveillance of a residence connected to the telephone network by a local loop consisting of a pair of copper wires, the usual practice was to locate a convenient cross connect and bridge on to the two wire analog circuit. The entity conducting the surveillance then engaged the serving telephone network operator or company to provide a circuit from that location to the law enforcement location. The law enforcement organization could then monitor the conversations, generally referred to as content, as well as the call set up and related signaling. Statistically approximately 90 percent of the authorized surveillance in the United States does not cover content but signaling data. Such events are referred to as Pen register taps.
With the widespread use of digital communication and control signaling, the simplicity and ease of the prior surveillance procedures has largely disappeared. As a result, law enforcement agencies, and cooperating Public Switched Telephone Networks (PSTNs), are forced to cope with a considerably more complex and costly substitute set of procedures. Partially in response to this situation Congress passed Public Law 103-414, the Communications Assistance for Law Enforcement Act (CALEA). The Telecommunications Industry Association (TIA), accredited by the American National Standards Institute (ANSI), was selected by the telecommunications industry to promulgate the industry""s CALEA standard. TIA promptly initiated a standards program. Initial disagreements within industry were resolved, and TR45 Lawfully Authorized Electronic Surveillance SP-3580, Baseline Revision 10 was produced. These have become known as the xe2x80x9csafe harborxe2x80x9d standards pending resolution of still outstanding differences with respect to certain preferences of the Federal Bureau of Investigation (FBI).
The CALEA specifications include the requisite that the target for surveillance continue to be provided with all subscribed enhanced, CLASS, and other services, and that the surveillance be completely transparent. The central office switches currently in use in the public switched telephone networks were not designed with CALEA functions in mind. As a result it is not surprising that not all types of existing switches are readily adapted to operate in a network that meets major CALEA requirements.
The basic surveillance problem has undergone continued evolution as telecommunications technology has advanced and provided the public with an ever-increasing variety of services. Illustrative of such services, which create added complexity for effective telephone surveillance, is call forwarding and particularly remotely activated call forwarding. Another example is central office based speed dialing.
Since the proposed CALEA requirements are worded in terms of service, i.e., monitoring the telephone service (signaling and speech) of the subject, and anything that can be accomplished with the service, significant problems are presented. This becomes particularly acute when coupled with a desire that the surveillance preferably be near universally applicable to all telephone central offices, including end offices that rely on legacy switches. One example of a specific problem is encountered with end offices using Lucent (formerly ATandT) 1AESS switches. These switches are among the earlier variety of stored program controlled switches and are rapidly being retired. As a consequence, it would not be wise to expend large sums to develop CALEA feature software for these switches. On the other hand the later Lucent 5ESS switches will be in service for many years to come and it may make sense to develop the requested surveillance capabilities in a number of network configurations. Cost considerations weigh heavily in selecting and providing an acceptable solution.
It is accordingly an object of the present invention to provide a relatively straightforward and cost effective solution to the foregoing problem.
For some years, the telephone industry has been developing an enhanced telephone network, sometimes referred to as an Advanced Intelligent Network (AIN), for providing a wide array of new voice grade telephone service features. In an AIN type system, local and/or toll offices of the public telephone network detect one of a number of call processing events identified as AIN xe2x80x9ctriggersxe2x80x9d. An office which detects a trigger will suspend call processing, compile a call data message and forward that message via a common channel signaling (CCS) link to a database system, such as an Integrated Service Control Point (ISCP) which includes a Multi-Services Application Platform (MSAP) database. If needed, the ISCP can instruct the central office to obtain and forward additional information. Once sufficient information about the call has reached the ISCP, the ISCP accesses its stored data tables in the MSAP database to translate the received message data into a call control message and returns the call control message to the office of the network via CCS link. The network offices then use the call control message to complete the particular call. An AIN type network for providing an Area Wide Centrex service, for example, was disclosed and described in detail in commonly assigned U.S. Pat. No. 5,247,571 to Kay et al., the disclosure of which is entirely incorporated herein by reference.
In an AIN network developed by the Regional Bell Operating Companies (RBOCs) and Bell Communications Research (Bellcore), a terminal and software system referred to as xe2x80x98SPACExe2x80x99 functions as the service creation environment and/or service provisioning system for the AIN control functions in the Service Control Points (SCPs) and Integrated Service Control Points (ISCPs) For example, as disclosed in U.S. Pat. No. 5,241,588 Babson, III et al., customized call processing information records are created and/or modified in a graphical environment, by creating or modifying a customer""s service graph on the display terminal. Data corresponding to the service graph is then stored in the SCP. Other terminal and software systems could be used to create and provision the AIN services. For AIN services today, however, telephone company personnel widely utilize the SPACE system to create templates for the service logic for new services. When customers subscribe to the services, the templates are filled in with the subscribers"" data to create individual call processing records (CPRs). The CPRs are stored in a database in the ISCP, for controlling actual call processing.
Many of the enhanced communication services offered by the AIN control system permit a subscriber to input control information, to manage services as desired. For example, in a simple call forwarding or redirection service, the subscriber may activate or deactivate the forwarding feature and may change the xe2x80x98forward toxe2x80x99 number from time to time to route calls to different destinations.
Typically such a call forwarding service may be activated by subscribers dialing an activation code followed by a local or toll telephone or directory number (DN). Thereafter, until the subscriber dials a de-activation code, the switching system forwards all of the subscriber""s calls to the thus entered forwarding directory number. In effectuating this service a party served by a local SSP switch office and who subscribes to call forwarding service has stored in the memory at the office, data identifying the party as a subscriber. In addition data is also stored at the office indicating if the service is activated and, if so, a directory number to which incoming calls are to be forwarded. When an incoming call is received the stored program of the office directs the interrogation of the memory data associated with the called station to determine if the called party subscribes to call forwarding service. If not, or if the service is not activated, the call is completed to the called station in ordinary fashion. However if a call forwarding service is active for the called party the stored program obtains the forwarding number from memory and from that point acts effectively as an originating office with respect to the new number. That is, the office may complete the call locally to the new number if it is served by the office, or it may seize an outgoing trunk to another local office or to a toll network, as the situation demands, and outpulse the new number to a distant office to complete the call.
With standard call forwarding, programming is accomplished either from the subscriber""s primary DN or manually by a technician at the Record Change Memory Administration Center (RCMAC), using the Remote Memory Administration System (RMAS). Conventional Call Forwarding provides an access code and a series of prompts to guide the customer through the call forwarding programming sequence. Recently there has been implemented a new feature which may be referred to as Remote Access to Call Forwarding (RACF). With Remote Access to call forwarding a subscriber can utilize any telephone equipped with DTMF signaling capability, dial a special access number, followed by a Personal Identification Number (PIN), and then dial additional codes in order to activate or deactivate the call forwarding feature.
An improved version of a system for providing such call forwarding is described in commonly assigned Hanle et al U.S. Pat. No. 5,012,511, issued Apr. 30, 1991, titled Method of and System for Control of Special Services by Remote Access. That patent is incorporated by reference herein in its entirety. One version of the system described in the Hanle et al. patent for remotely programming switches, uses multiplexing of processed recent change signals delivered to the switch. This particular version of the Hanle et al system provides very prompt, approaching virtually real time, effectuation of callforwarding instructions. In this procedure the instructions pass through and are stored in a node which may be located in a multi-services application platform (MSAP).
In a public switched telephone network, interoffice call attempts to or from a line under surveillance generate a variety of query, response and release messages between the offices, as part of the normal procedures for setting up and tearing down the calls to and from the line. According to one feature of the invention means are provided to insure that all calls to or from a line under surveillance generate signaling messages. This is accomplished according to one embodiment of the invention by setting terminating, dialing, and release triggers with respect to the target line, as well as any lines that may become associated with the target line. As a result, the end office serving the target, which may or may not be the end office to which the target""s local loop line is attached, sends queries to a database on the signaling network, receives response messages, and sends release report messages, even for intraoffice calls. These messages include all of the call set-up and tear down messages, as well as the query, response and release report messages communicated between the office and the database.
A site processor, acting as a data filter, compiles data from all of the signaling messages relating to each individual call, to or from an identified telephone number or line (the target). The site processor forms a call detail record (CDR) for each call attempt relating to an identified target under surveillance. Site processors associated with multiple switches involved in surveillance activities may upload CDRs to a central file server for parsing, sorting and further processing. The server supplies composite data regarding calls to and from targets under surveillance through a data network connection to processors of one or more law enforcement agencies. The activities involved are transparent to the called and calling parties.
Caller ID signals reflect the target line despite the fact that such would not typically occur with conventional PSTN network architecture and procedures which may be utilized. Likewise billing is controlled to insure that no detail in those procedures indicates that anything but normal telephone service is involved. With respect to call forwarding, signaling information relating to installation of the service, activation and de-activation, and the identification of the forwarding number or numbers are collected at multiple nodes in the system. The necessary information to conduct surveillance on forwarded calls is then derived or forwarded from the appropriate node or nodes in order that the surveillance may be complete.
Pursuant to one feature of the invention the advanced intelligent network is used in conjunction with programmable monitors to trap and temporarily store or record predetermined data associated with designated call attempts, call set-up, call tear down, originating and destinating directory numbers, call duration, and other information with respect to the telephone activities of parties under surveillance. This information from monitors in one cluster is stored in a site controller for that cluster. That information and similar information gathered from site controllers for other clusters is sent to a central controller server and from there is distributed via a telephone network intranet to the surveillance center. Under the direction of a telephone network management system information from other sources in the network is likewise forwarded via the telephone network intranet to the surveillance center.